Landfill leachate generated from open MSW dumpsite can cause groundwater contamination. The impact of open dumping of MSW on the groundwater of adjacent area was studied. To assess the spatial and temporal variations in groundwater quality, samples were collected around an open MSW dumping site in Ranchi city, Jharkhand, India. Groundwater samples were analysed for various physicochemical and bacteriological parameters for 1 year. Results indicated that the groundwater is getting contaminated due to vertical and horizontal migration of landfill leachate. Extent of contamination was higher in areas closer to the landfill as indicated by high alkalinity, total dissolved solids and ammonia concentration. Metals such as lead, iron, and manganese were present at concentrations of 0.097, 0.97 and 0.36 mg/L, respectively exceeding the Bureau of Indian Standards (BIS) 10,500 for drinking water. Enterobacteriaceae were also detected in several groundwater samples and highest coliform count of 2.1×10(4) CFU/mL was recorded from a dug well. In order to determine the overall groundwater quality, water quality index (WQI) was calculated using weighted arithmetic index method and this index was further modified by coupling with the analytical hierarchy process (AHP) to get specific information. WQI values indicated that the overall groundwater quality of the region came under "poor" category while zone wise classification indicated the extent of impact of landfill leachate on groundwater.

Sequencing batch reactor (SBR) was assessed for direct co-treatment of old landfill leachate and municipal wastewater for chemical oxygen demand (COD), nutrients and turbidity removal. Nitrogen removal was achieved by sequential nitrification and denitrification under post-anoxic conditions. Initially, SBR operating conditions were optimized by varying hydraulic retention time (HRT) at 20% (v/v) landfill leachate concentration, and results showed that 6 d HRT was suitable for co-treatment. SBR performance was assessed in terms of COD, ammonia, nitrate, phosphate, and turbidity removal efficiency. pH, mixed liquor suspended solids, mixed liquor volatile suspended solids (MLVSS), and sludge volume index were monitored to evaluate stability of SBR. MLVSS indicated that biomass was able to grow even at higher concentrations of old landfill leachate. Ammonia and nitrate removal efficiency was more than 93% and 83%, respectively, whereas COD reduction was in the range of 60–70%. Phosphate and turbidity removal efficiency was 80% and 83%, respectively. Microbial growth kinetic parameters indicated that there was no inhibition of biomass growth up to 20% landfill leachate. The results highlighted that SBR can be used as an initial step for direct co-treatment of landfill leachate and municipal wastewater.

Effects of open dumping of municipal solid waste on local groundwater microbiology were assessed in Ranchi, India. Both the spatial and temporal variations of groundwater microbiology were studied. Groundwater was analyzed to determine heterotrophic plate count (HPC), total coliforms (TC) and faecal coliforms (FC). Highest HPC was 4.5 × 104 CFU/mL and the highest total coliform count was 3.7 × 104 CFU/mL. Faecal coliforms were detected in most of the groundwater samples. The highest faecal coliform count of 2.1 × 104 CFU/mL was from a hand pump located adjacent to the dumping site. Spatial variations revealed dispersion of bacterial contamination up to 5 km from the periphery of the municipal solid waste dump. The level of bacterial contamination decreased with an increase in distance from the municipal solid waste dump. The maximum bacterial count was detected in the monsoon whereas the lowest count was found in summer. Molecular characterization of morphologically similar faecal coliform colonies indicated the presence of Klebsiella pneumoniae (Klebsiella ssnkbit, KU647674) in one of the groundwater samples which showed maximum faecal coliform count. Results of this study indicated that groundwater in the area is highly contaminated with a bacterial load which can be a major health risk.

The use of novel flocculants in combination with a sequencing batch reactor (SBR) for the treatment of landfill leachate and municipal wastewater has been shown to be an effective method for reducing polluted effluents. Co-treatment of landfill leachate with a mixture of municipal wastewater was performed at 5%, 10%, 15% and 20% in SBR and effluent was treated by coagulation–flocculation. SBR with 6 d hydraulic retention time (HRT) and 30 d solids retention time (SRT) removed 58 to 70% COD, 86 to 93% ammonia, 76 to 83% nitrate and 69 to 95% phosphate. Coagulation–flocculation with different dosages of alum and ferric chloride with polyacrylamide grafted gum ghatti (GGI-g-PAM) as a novel flocculant was used for chemical oxygen demand (COD), turbidity, total suspended solids (TSS) and color removal. Maximum COD removal was at 20% leachate, which was 74% with alum at 2800 mg/L and 77% with ferric chloride at 470 mg/L. Alum and ferric chloride with GGI-g-PAM flocculant removed 96% and 82% of turbidity and 80% and 82% TSS, respectively. At 20% leachate, combined treatment with SBR and coagulation–flocculation resulted in the total removal of 89% COD, 83% ammonia, 82% nitrate 98% turbidity and 93% TSS with alum. The combined treatment with ferric chloride resulted in a removal of 90% COD, 86% ammonia, 83% nitrate, 98% turbidity and 94% TSS. Except for nitrate combined treatment with both the coagulants at 20% landfill leachate to municipal wastewater ratio removed COD, ammonia, phosphate and TSS to a level that met international standards for discharges to inland surface water. As such, the use of new flocculants with SBR can help reduce water pollution from landfill leachate and municipal wastewater. In addition to coagulation–flocculation, other physico–chemical processes can also be studied as post-treatment options for the co-treatment of wastewater mixture.